From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Sachin Shelar" Subject: kernel module acquiring virtual ip's Date: Thu, 27 Apr 2006 14:34:49 +0530 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; format=flowed; delsp=yes; charset=iso-8859-15 Content-Transfer-Encoding: 8bit Return-path: To: netfilter-devel@lists.netfilter.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: netfilter-devel-bounces@lists.netfilter.org Errors-To: netfilter-devel-bounces@lists.netfilter.org List-Id: netfilter-devel.vger.kernel.org Hi, I have a kernel module which "acquires" virtual ips ( not assigned to anyone in n/w ) and then respond to any future packets coming to this virtual ip. I am handling ARP, TCP, UDP protocols in my module. To get the arp stuff working I handle all the ARP requests for virtual IP and reply to them with my local hardware address. I can now receive all the packets destined to virtual IP. E.g Local IP is 192.168.1.2 Virtual ip is 192.168.1.244 ( Not existing in network ) I catch every arp request for .244 and reply with my mac. I can now recive all IP packets ( handled in my netfilter hooks ) destined for .244. According to the natting rules in my module I nat the packets for .244 and redirect them to some listening port on 192.168.1.2 Also I handle all the outgoing packet from 192.168.1.2 and replace the source to 192.168.1.244 So that the client machine recives reply from virual IP, as expected. 192.168.1.21[32774] -> 192.168.1.244[123] Nat Destination 192.168.1.21[32774] -> 192.168.1.2[23] (Reply) 192.168.1.2[23] -> 192.168.1.21[32774] Nat Source 192.168.1.244[123] -> 192.168.1.21[32774]. Module works perfectly and I can establish any tcp connection ( E.g telnet ) with a non exitsing IP ( 192.168.1.244) from any machine in the network. Problem is :- =========== I want the same behaviour from the module if I try to connect from the same machine (local machine ) to the virtual IP. E.g 192.168.1.2[32772] -> 192.168.1.244[123] Nat Destination 192.168.1.2[32772] -> 192.168.1.2[23] ***** But somehow this packet after natting is dropped by the kernel and never reaches 192.168.1.2[23] Is this because the source and destination ip of this packet is same ????? Whats the solution for sending a packet with local ip as its src and dst to local from POSTROUTING hook Thanks, Sachin